the sos sub is a decent selection. sounds pretty nice. It does take away some footwell space (wife's 5'4" and likes to complain about it when sitting in passenger side), but if you usually drive by yourself it won't make much of a difference. I do 95% solo driving, so it took me about 2 months to realize i'd lost a bit of space.
I'm sure most subs out there cause a loss of space. just the price of fame i guess. i will say the install was very clean, and visually you literally cannot tell the sub is there till you try to stretch out the toes a little bit. so cosmetically it's perfect..